Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in PYTHON3):

Solution:
h,w=map(int,input().split())
g=[input() for _ in range(h)]
d=[[-1]*w for _ in range(h)]
d[0][0]=0
q=[(0,0)]
while q:
  tx,ty=q.pop(0)
  for dx,dy in [(1,0),(0,1),(-1,0),(0,-1)]:
    nx,ny=tx+dx,ty+dy
    if 0<=nx<h and 0<=ny<w and g[nx][ny]=='.' and d[nx][ny]<0:
      d[nx][ny]=d[tx][ty]+1
      q+=[(nx,ny)]
print((sum(s.count('.') for s in g)-d[-1][-1])*(d[-1][-1]>0)-1)